You've just shelled out thousands of dollars for solar power, but what if your shiny new solar panels are underperforming?

Solar installer SolarCity on Monday is expected to announce a system that lets businesses and home owners get a real-time readout of their solar panels from a Web portal.

Called SolarGuard, the monitoring system collects data on system performance, which is then transmitted back to SolarCity every 15 minutes.

The idea is that problems can be identified and service technicians can go out to fix the problem quickly after analyzing the data coming in from customers, according to the company.

To make the free service work, SolarCity customers need to install a small black box that attaches to their Internet router.

The company said the monitoring service is a way to ensure that a solar installation performs as it should over the anticipated life of the system. Typically, panels have a warranty of 20 to 25 years.

Getting accurate information on solar panels' output is not necessarily easy to do: people can compare old bills with new bills, but several factors such as weather can make comparisons hard.

Reliable data is particularly important to commercial customers, who make long-term budget assumptions based on energy performance.

This need for information is spawning a market for solar-related software. Fat Spaniel Technologies specializes in monitoring solar-panel performance. Another company called GridPoint sells an entire system, including storage, that includes an Internet service for monitoring and analyzing solar-panel output.

About the author

Martin LaMonica is a senior writer covering green tech and cutting-edge technologies. He joined CNET in 2002 to cover enterprise IT and Web development and was previously executive editor of IT publication InfoWorld.
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